In general, Cruise Control (CC) system is aimed at reducing driver's burden by partially automating acceleration/deceleration control of a vehicle in a driving direction.
A vehicle with the CC system is controlled to maintain a target speed when there is no vehicle ahead, and to keep, when there is a preceding vehicle ahead, a safe distance to the preceding vehicle.
When the vehicle runs uphill, it decelerates gradually if the driver does not put down the accelerator. However, if the CC system is installed in the vehicle, the vehicle is controlled to maintain the target speed without being decelerated by increasing fuel amount that is supplied to the engine.
If the vehicle is equipped with the CC system and being accelerated when running downhill so as to exceed a maximum target speed, the vehicle no longer performs acceleration/deceleration control automatically, or performs brake control for a long time in order to maintain the target speed.